1. Field of the Invention
The present invention relates to a gas discharge tube. More particularly, it relates to a gas discharge tube preferably applied to a display device in which the gas discharge tubes, made of elongated tubes, of a diameter of about 0.5 to 5 mm are arranged parallel to each other to constitute a display screen.
2. Description of Related Art
In general, PDPs (plasma display panels), known as panels for large-scale display, are so constructed that a pair of substrates each having electrodes formed thereon are disposed opposite to each other with a periphery thereof sealed and a discharge gas enclosed in a discharge space defined between the substrate pair. Apart from such PDPs, display devices in which a plurality of luminous bodies (tubular luminous bodies: gas discharge tubes) are arranged parallel to each other are also known.
In the above display devices, electrodes are formed outside (or inside) elongated, hollow, glass tubes of a diameter of about 0.5 to 5 mm, and luminous bodies having a discharge gas enclosed therein and phosphor layers formed on an internal wall surface are arranged in a row direction (or in a column direction) to constitute a display screen. As such display devices, are known a large-scale gas discharge display panel described in Japanese Unexamined Patent Publication No. Sho 61(1986)-103187, an image display device described in Japanese Unexamined Patent Publication No. Hei 11(1999)-162385 and the like.
These display devices having the gas discharge tubes and used for large-scale display are advantageous in reduced number of fabrication steps, reduced weight and costs, and ease of screen size change.
However, in the gas discharge tubes applied to such display devices, it sometimes occurs that the discharge gas within the discharge tube tends to be contaminated, thereby affecting the discharge characteristics. Namely, the discharge tubes have so small a diameter that water, carbon dioxide or the like adsorbed on surfaces of secondary electron emission layers or the phosphor layers is difficult to sufficiently remove when impurity gases are evacuated. This incurs a problem of impurity gases being liable to generate from the secondary electron emission layers or the phosphor layers formed in the gas discharge tubes during electric discharges generated by the discharge gas enclosed in the discharge tubes. Moreover, the discharge tubes have a volume so small as to be affected severely by the impurity gases.